Description:
The Colorado Front Range has formed, bringing mountain topography back
to Colorado for the first time in nearly 200 million years. Warm air and
plentiful rainfall promote a bounty of plant life. Huge plant-eaters such
as Triceratops
browse in a forest of palm tree thickets and patches of paddle-leaved
plants. Climbing
ferns, herbaceous
plants, and a variety of broad-leaved trees also grew here. Home to
hundreds of turtles, birds, lizards, tiny mammals, frogs, and snakes,
this landscape is also the turf of Tyrannosaurus
rex, the largest meat-eating animal in North American history.

Like the Pierre Shale, the Denver Formation is rarely found as outcrops.
This is the rock layer that lies below downtown Denver. This picture
was taken at a roadcut on the side of I-70 about thirty miles east
of town. The Denver Formation is exposed in the cut beneath the
overpass.